Eosinophilic esophagitis (EoE) is a rare disease of children and adults characterized by symptoms such as nausea, vomiting, abdominal pain, dysphagia, and food impaction, that occur in conjunction with esophageal eosinophilia. To date, the only method to make the diagnosis and follow treatment responses in EoE is invasive endoscopy with biopsy. While endoscopy is generally safe, an accurate, less invasive, inexpensive, comprehensive and durable test is needed to determine therapeutic efficacy. To address this need, the investigator proposes the use of a novel application of an existing technology, the Enterotest ?(a string based test used to detect intestinal Giardiasis), to measure esophageal inflammation (herein termed the Esophageal String Test or EST). The investigator states that preliminary data provide proof-of-principle for the ability of ESTs to capture esophageal inflammatory mediators in luminal samples from patients affected with eosinophilic esophagitis, demonstrating that: (1) levels of eosinophil-derived granule proteins in esophageal mucosal biopsies correlate with the levels quantitated in the EST-captured samples, i.e., levels in luminal secretions captured by the EST correlate with mucosal inflammation, and (2) these luminal biomarkers of eosinophilic inflammation significantly correlate with EoE disease activity. According to the investigator these findings support the use of ESTs as novel minimally invasive instruments to monitor therapeutic efficacy in eosinophilic esophagitis. The Specific Aims of the proposed Phase 2, multicenter study in 660 children and adults are to: (1) identify an eosinophilic esophagitis biomarker panel that will improve the sensitivity and specificity of the EST for monitoring disease activity, and () validate the ability of the EST esophagitis biomarker panel to monitor therapeutic efficacy in 1-hour sampling time. The investigator states that preliminary data demonstrate the feasibility of using the EST in both children and adults with EoE to measure disease activity (esophageal inflammation) in an overnight (12-hour) test, and shorter time periods, currently performed before a scheduled endoscopy with biopsy. In this project investigators propose to shorten this time frame to a 1-hour test, a clinically relevant time point that is believed to facilitate use an potential impact in the outpatient clinic setting.